Future history of the Pentagon War universe:

(A number at the beginning of a paragraph indicates mean Solar [Earth] year,
with year 1 being arbitrarily set as the year of first contact between humans
and Centaurians. Humans still use the Gregorian calendar year;
Centaurians use their own calendar except when communicating with humans.
For reference, the year "x" is sometimes called "x AC", with AC being variously
interpreted as "Alpha Centauri", "After Centaurians", or "Anno Contacti".)

-43 – Manned (or should I say Centaurianned) survey of Alpha Centauri B
performed by the Centaurians. The second planet from the star is found to
harbor life; however, nothing more advanced than a trilobite-like species has
evolved.

-38 – First colonists sent to Alpha Centauri B II. The oxygen
atmosphere means there is no need for terraforming — er,
A-III-forming. However, all native life is completely inedible, so
imported grains have to be planted. These eventually get out into the
wild and begin displacing the native autotrophs. A mass extinction of
native life begins; the colonists must study the ecosystem rapidly before it
is so disrupted as to be nothing like what it once was.

-35 – Centaurians lay plans for a spacecraft using what humans would call
the Bussard interstellar-hydrogen-collection principle. They have not yet
overcome the ramscoop drag problem, so this spacecraft's top speed is limited
to its own exhaust velocity. It is to be sent to Alpha Centauri Proxima.

-30 – First Centaurian ramscoop completed and sent on its mission to
Proxima. In the years that follow, new designs emerge that could make the
trip considerably faster, but the Centaurians figure, hey, we can wait, it's
only Proxima Centauri. Their attitude turns out to be completely correct.

-15 – Details of the bleak, lifeless rendezvous with Proxima Centauri
reach Alpha Centauri A III. These results aren't too surprising, seeing
how ol' Alpha Centauri C is a flare star. Centaurians realize they're
going to have to literally reach for the stars if they want any hope of
contacting another intelligent species. Several decades ago, the Sol
system nearly doubled its total radio energy output; some Centaurian
astronomers have interpreted this as a sign of emerging technological life in
that system.

-9 – Centaurians complete their first true starship, a
proton-fusion-powered Bussard-like Scramjet, which can fuse collected hydrogen
in a lengthy QC&C reactor that doesn't slow the incoming materal
down. A vast interstellar plasma deflection field makes up the majority
of the craft's "scoop", and is tuned to create drag during the deceleration
phase (as well as collect some hydrogen to replenish the fuel tanks).
This spacecraft does have to carry some fuel for the "boost" phase (it can't
gather a lot of interstellar medium below about 10% of c or so), giving
it a modest 3-to-1 fuel-to-empty-mass ratio. They put a crew aboard it
and accelerate it at a steady 0.8 g toward their nearest Truly
Interstellar neighbor, Sol.

1 – Arbitrary [Earth] year some time in the 21st century. First
contact with Alpha Centauri is made. We detect their starship on its way
to the inner Solar system, it enters a direct circular orbit about the Earth at
an altitude between the two Van Allen belts, everybody gets jumpy, and then
some paranoid general orders two ground-lanched tactical nuclear missiles
(which were originally ICBMs for use against strategic thermonuclear launchers)
to attack the starship as their target. The Centaurian spacecraft is
blown to pieces in a fission fireball. (The Centaurians had never
encountered nuclear weapons before, and weren't expecting to get shot at
anyway. The only other place they'd found life had been Alpha Centauri B
II.) The U.S. government, which had been working toward being the World
Federal Government anyway, kind of takes over and launches a massive defense
program, and redesignates its Air Force as its Space Force, to prepare for the
inevitable Alpha-Centaurian counterattack.

2 – Analysis of the fragments from the destroyed Centaurian spacecraft
show that it was almost certainly a Bussard-Ramscoop-like design. It also
seemed to be able to force ordinary light-hydrogen (protium) to undergo
controlled, sustained fusion. Although the engine assembly is in nowhere
near one piece, the QC&C core is more-or-less intact. The painstaking
process of reverse-engineering QC&C technology begins. This helps to
further prepare for the inevitable Alpha-Centaurian counterattack.

3 – World Federal Government formed. In some ways it's less
oppresive than the previous national governments it supplants; in other ways,
it's more oppressive. In less than two decades, though, this won't
really matter.

15 – The inevitable Alpha-Centaurian counterattack. Some of the
paranoids heading up the Alpha Centauri government perceived Sol as a potential
threat to their own home soil, reasoning that any species that could vaporize
one of their spacecraft in one stroke must also be at least that much farther
ahead of them in interstellar travel capabilities. (We're not, they're
just afraid we are.) Ten combat-oriented interstellar spacecraft (all
proton-fusion scramjets) enter low Earth orbit, looking for missile launch
sites to shoot down. Nuclear missiles converge on them both from ground
launch sites and newly-installed orbital launchers, but this time the
Centaurians manage to shoot them down before they hit their spacecraft.
Well, most of them, anyway — a few get through and destroy seven of the
ten Centaurian craft while crippling another. The crippled starship has
to be abandoned in orbit. Big
fighting ensues. Ground sites where missiles and suspected missiles are
stored are attacked by the Centaurians from orbit. Troops at these sites,
of course, die. After a few [Earth] days, the fighting reaches an uneasy
cessation, and the Centaurians send down an illustrated dictionary and analog
LP-like recordings of their language. The World Federal (formerly U.S.)
Government responds by sending them an illustrated English dictionary and some
digital optical discs (mostly to boast about the level of our
technology). Although their language is unpronounceable to a human vocal
mechanism (while our discs are, at the time, beyond their ability to read),
communications are established, diplomats meet behind hermetically-sealed
windows, and the Centaurians and Humans agree to an uneasy ceasefire —
which, of course, leads to a cold war by both sides. Having seen the real
state of our space capabilities, the Alpha-Centaurians no longer consider
humankind to be as much of a threat as previously supposed. Captured
human satellites provide the Alpha-Centaurians with a computer technology the
likes of which they have never seen before. Conversely, the one abandoned
Centaurian craft was in good enough shape that humans were able to figure out
the final secrets of its QC&C proton-fusion scramjet engine; this marks the
beginning of the end of the Ballistic Age of Space Exploration.

16 – First QC&C proton-fusion electric power plant begins
operation. It's a single-stage proton-proton reactor, originally designed
to address the burgeoning market for deuterium and sell its electric output as
a by-product. As the supply of deuterium skyrockets, however, the reactor
quickly shifts its business focus to the power generation market. The
process is so cheap and efficient that within two decades, no other kind of
large scale power plant (other than the hydroelectric dam) is in use anywhere
on Earth. The Age of Cheap Energy begins. With deuterium now
available in such great abundance, both protium-deuterium hot fusion and
QC&C deuterium fusion allow humans to really pick up the pace of space
exploration and exploitation. Humanity had already gotten its act
together with every aspect of spaceflight except launch costs; now, boosting
people and cargo into or past Earth orbit is no longer a big deal, and orbiting
spacecraft construction facilities spring up practically overnight. Human
colonies on Earth's moon follow almost immediately.

19 – Alpha Centauri learns of the shaky armistice reached on Sol's third
planet and decide they need to develop an antimatter arsenal. Positron
collectors and starlight-powered antiproton factories are set up on Proxima
Centauri's first solid planet. (Proxima's flare activity means its
planetary system must remain uninhabited, which makes it ideal for dangerous
operations such as antimatter manufacture.) [Note: at this point in
history, antiprotons are considered the most useful form of antimatter, since
they are 2000 times heavier than positrons and, thus, more grams can be herded
into magnetic bottles more easily. Positron collecting is only of fringe
interest to any star system's military.]

20 – Martian colony follows soon after the lunar one, and terraforming
begins (in the form of planting lots of dark-colored plants wherever there
might be water). Humans begin colonization of the larger asteroids and
the Galilean moons. The World Federal Government that started these
colonies makes many overtures about freedom and self-sufficiency, but still
considers them subject to World Federal Government control; however, this
policy has yet to be tested.

21 – North Mars colonized.

22 – Colonel Ira Henderson makes his address to the Earth Committee for
Space Travel. Of the nearby star systems, Sirius, Lalande 21185, and
V1216 Sagittarii (alias Ross 154) are at the top of the list of candidates for
colonization.

23 – Mars and North Mars colonies grow to each others' borders.

24 – The Mars/North Mars conflict. After months of bloody fighting,
Earth intercedes by taking strict control of both of them. (At an average
opposition, a 1g brachistochrone flight from Earth to Mars would take
about 2 days. At an average conjunction, it would take four-and-a-half
days.) This marks the solid beginning of the transition from the World
Federal Government to the Solar Federal Government.

27 – Alpha-Centaurian "check up" starship arrives in Sol space and
reports current state of events to Alpha Centauri. The starship's
personnel consist of one very large Centaurian clan. Some of the visiting
Centaurians decide to stay in North Mars, forming their own split-off clan (and
coining their new clan's name on the spot.) The World/Solar Federal
Government's constabulary in North Mars allows it. They're greeted with
open arms; but as soon as the starship leaves, their human hosts order them
into confinement under armed threat. One of the Centaurians, when told
the implement being pointed at them is a deadly weapon, shrieks and charges at
the gunman, who shoots and kills the Centaurian. The rest are rounded up,
quarantined, and studied intently (two of them with microscopes and scalpels)
— but not before some of each species' xenobacteria are exchanged.
The way in which the Federal Government lured these Centaurians into their
clutches is to blame for the lack of epidemiological precautions. While
on its way out of the Solar system, the check-up spacecraft surreptitiously
leaves some hard-to-detect reconnaisance satellites between the orbits of
Uranus and Neptune. Our progress disturbs them. When the humans
find one of these satellites, they too are disturbed by this interstellar spy
and figure the best course of action is to branch out outside of our own star
system. The SBI is formed, and the first plans for the colonization of
Sirius are begun.

28 – One of the many strains of airborne Alpha-Centaurian bacteria to be
brought to North Mars causes a lethal epidemic there. Over a quarter of
the human population in North Mars dies before the disease is contained and an
anti-xeno-biotic is developed. Conversely, plain old harmless-to-humans
E. coli kill each and every one of the quarantined Centaurians, since
the visiting Centaurians had no natural resistance and weren't equipped to
handle a plague. Before all the captive Centaurians die, though, the
clan's medical expert provides crucial assistance to their human captors,
helping them to ultimately find a cure.

30 – Bussard scramjet starships, though much smaller than the designs the
Alpha-Centaurians visited us in, leave Sol for Sirius en masse.
And not all Federally backed, either. Several rag-tag groups of people
that can't stand the Federal government take off to Brave the Wilds
themselves. As do some criminals, much like the indentured servants that
came to America in the 17th and 18th centuries. The Federally-backed
starships carry a small army of assembly robots that can mine and smelt the
native ores, build QC&C generators, construct housing, raise food crops,
etc.. However, as it turns out, these robots can also be programmed to
assemble military hardware as well. Since each scramjet can only carry
a couple dozen people tops, they also carry along an ample supply of frozen
embryos, and each of the women must agree before departure to implant pairs of
these frozen embryos in her uterus, and thus bear twins, over-and-over again
for the rest of her healthy adult life once they reach their destination.
This is the only way the colony can reach a stable population size in a short
time, and raise these children in families large enough to rival a full
school classroom. Nearly all the colonists are women; due to their
constant pregnancy and the demands of child rearing, assembly 'bots are
expected to be the primary labor force. [Note that at this time,
hibernation technology has not yet been discovered by humans. These
colonists have a long ride ahead of them.]

32 – A second wave of small starships, all Federally backed, depart Sol
for Sirius.

34 – Via their outer-Sol-system-orbiting satellites, the
Alpha-Centaurians learn of our colonization fleet and send a small fleet of
their own to Sirius. They also like our idea of colonizing a new star
system and, fearing Sirius might be used as a second staging area for human
military assaults, send out a slightly larger colonization fleet to CN Leonis
(alias Wolf 359), consisting mostly of malcontents. (V1216 Sagittarii,
while closer, larger, and with less frequent flare activity, has bigger
flares when they do occur; plus, it has a lower abundance of heavy elements,
making its resources both scarcer and harder to exploit. UV Ceti has
so much flare activity as to be uninhabitable.)

36 – By this time, all the cheap energy created by QC&C fusion on
Earth has ushered in a worldwide post-scarcity economy. Government
oppression is no longer an issue, since starvation (or even the threat
of starvation), which drives the kind of strife that prompts most government
intervention, has become a thing of the past. Poverty, in the sense of
some being wealthier than others, still exists, but a "poor" person in this
world never has to worry about life's necessities.

39 – The fledgling SBI reports the outbound Centaurian starships to the
Solar Federal government on Earth. Two spacecraft were positively
identified as being aimed for CN Leonis; the rest could not be pinned down as
to their destinations. Sol assumes the entire Centaurian fleet is headed
there.

40 – Sol: Several armed starships are sent to CN Leonis.

42 – Sirius: First human interstellar scramjets arrive at Sirius
A. The fourth planet from the star lies closer than the traditional
Comfort Zone, yet, because of the extremely low CO2
content of its atmosphere, has pre-aerobic life on it at the middle-to-high
latitudes. Colonies are established and terraforming slowly begins, with
an eye on keeping CO2 levels down. The population of this
new colony is frighteningly low — you can only make an interstellar
scramjet so heavy before you reach the upper limit of how wide your scoop field
can be — but thankfully they brought along robotic assemblers to help
build their infrastructure. Eight-and-a-half light-years worth of
distance from their original home makes the three months of travelling time
between England and colonial America look like a trip around the block.

44 – Second wave of starships arrive at Sirius. These more gung-ho
Solar Federalists quickly learn just how much On Their Own they really
are. It doesn't take long for Sirius to declare its independence.

47 – First Alpha-Centaurian scramjets arrive at CN Leonis.
Colonization of CN Leonis II begins. Since CN Leonis is a mild flare
star, CN Leonis II can never be terraformed (at least on its surface), but this
means its surface is ideal for setting up the antimatter production facilities
that nobody wants in their back yard. A period of "salutory" neglect
follows, during which the colonists engage in a massive military buildup.

50 – First Alpha-Centaurians arrive at Sirius. First thought to
be another wave of human colonists, the Sirians transmit the news of their
independence to them. When they discover that they aren't human at all
but Alpha-Centaurian, panic ensues, and the entire Sirian military is mobilized
against the starships. (A few of the scramjets the humans had made their
journeys in have been converted to weapons platforms, in anticipation of
attempts by Sol to re-take the system.) Being primarily colony spacecraft
and not expecting this kind of resistance, the visiting Centaurians soon
surrender. The secrets of the Alpha-Centaurian interstellar plasma
deflection fields, used in these colony craft, are unlocked by humans for the
first time; they are more efficient than the methods humans used for surviving
relativistic speeds. Since the starships' occupants are still alive and
can be questioned, the Sirians discover that certain cooling rooms on board
— which had been glossed over by analysts back on Sol when examining the
damaged Centaurian starship after Second Contact — are actually
hibernation chambers. Being cold-blooded, Centaurians will hibernate
whenever the temperature falls below 5° Celsius, during which time they
consume practically no food or water and little oxygen, and age at about 1/5
the normal rate. When Sirius broadcasts this discovery back to Sol,
human hibernation technology — once considered "too risky" — is
unshelved and given center stage, lest Sol suffers a "hibernation gap."

51 – CN Leonis: News of Sirius's declaration of independence
arrives. And so does Sol's military force, with gun ports open.
The Solar folks weren't expecting the massive military buildup that
had happened in the past five years, and the Leonians blast hell out of some
Solar spacecraft while capturing the rest. The prisoners (all of whom are
human) are paraded around on CN Leonis-II like captured slaves. News of
this little replay of the Bay of Pigs invasion has been sent back to Sol before
Sol's forces are completely vanquished, though.

52 – Sol: News of Sirius's declaration of independence arrives at
Sol. Sentiment among interplanetary colonists there, and even on Earth,
is mixed, so the Federal government can only send a small military force to
Sirius to restore order there without losing face. That military force
consists of one interstellar craft carrying four automated "fighter" spacecraft
which had originally been engineered to fight the Alpha-Centaurians.

59 – Sol hears about the victory at CN Leonis and decides to leave the
damn place alone — in part due to a small, grass-roots group of "learned"
citizens calling themselves Humans for Better Interspecies Relations.

60 – Alpha Centauri hears about the victory at CN Leonis, but only by
indirectly inferring it from the least official of their communications.
They're not sure who to be infuriated at more: Sol for attacking their colony,
or CN Leonis for not acting like they were an Alpha-Centaurian colony any
more. Not knowing how strong CN Leonis is, Alpha Centauri sends its own
military force there to prevent them from "breaking off" the way Sirius did
from Sol. Some concerned citizens become worried by all this warmongering
and begin stepping up personal correspondences with Solar citizens in an
attempt to bridge the species gap.

62 – "Peace Keeping" force from Sol arrives at Sirius. The Sirians,
who had been expecting such a turn of events, had converted some of the
scramscoops they made their journeys in into weapons-carrying spacecraft.
Although outmatched in terms of maneuverability by the fighters, the extra
armor plating and Alpha-Centaurian interstellar plasma deflection fields (now
beefed up to "battle screens") are all the edge the Sirians need. They
win the Sirian War for Independence in a matter of days.

65 – New slew of messages from the more concerned citizens of Alpha
Centauri reaches Sol. The Humans for Better Interspecies Relations grows
as a result.

66 – The Humans for Better Interspecies Relations cause a minor backlash
movement among some old-timers, resulting in the most hawkish election turnout
in twenty years.

70 – News of the outcome of Sirius's War of Secession reaches Sol.
The Solar Federal government grudgingly accedes to Sirian independence; it
works to the advantage of the hawks, who can now point to Sirius as a "new
outside threat" to further Sol's cold-war footing. The Humans for Better
Interspecies Relations are now the best place to go if you want to correspond
with a Centaurian in another star system.

71 – The Humans for Better Interspecies Relations reaches a critical
mass. Citing emotional-plague behavior and so-called "intolerance" as the
main cause of xenophobia, they announce the intention of building a new,
independent colony in a new star system, and send an open invitation to any
other humans or Centaurians who wish to join them. The only restriction
on citizenship in this new "Human-Centauri", they insist, is that emotional
plague behavior will not be tolerated, and that they will be free to deport any
emotional plague characters.

72 – Alpha Centauri's military force arrives at CN Leonis. The
fleet is devastated within minutes of announcing their role as enforcers.
Leonian independance has been waiting to happen, and this provides all the
impetus it needs.

75 – News of the Human-Centauri project reaches Alpha Centauri.
There is a large degree of interest — and some suspicion from the
Alpha-Centaurian government. The interested Alpha-Centaurian citizens
realize that the best solution to avoid interference from any of the three
existing governments is for Human-Centauri to be in a star system that nobody
else is interested in.

79 – Sirius: News of the Human-Centauri project arrives. Few
Sirians are interested. Sol: Agreeing with the interested
Alpha-Centaurian citizens, the Humans for Better Interspecies Relations have
already chosen one of the least interesting Human-Centauri locales imaginable:
a substellar ball of heavy-element-rich hydrogen named Haberd's Brown Dwarf
629. It didn't even manage to ignite into a star under its own weight,
but is large enough to be ignited artificially. (It's also situated
closer to Sirius and CN Leonis than to either Sol or Alpha Centauri.)
The brown dwarf also never underwent a planetary formation period, and is
instead surrounded by a densely-packed ring of orbiting debris. The first
wave of emigrants leaves for this newly-christened Human-Centauri system,
carrying with them an antiproton bomb which they figure will start a fusion
reaction within the substar.

79 – News of CN Leonis's sovereignty arrives at Sol.

80 – Sirius: News of CN Leonis's sovereignty arrives. (The
Leonians have enough of a resource base to feel comfortable in broadcasting
this fact, unlike Sirius.) Alpha Centauri: News of CN Leonis's
independence arrives. This causes Alpha-Centaurian government to fear
it's losing control and clamp down on its own populace somewhat. The
Human-Centauri enthusiasts get even more antsy to leave.

83 – Alpha-Centauri: News of the location of Human-Centauri
arrives. A few Centaurians back away out of skepticism over the ability
to "create" a star — not to mention the insane logistics of living in an
asteroid field that puts Sol's asteroid belt to shame — but in light of
the more militaristic political situation in their home system, most of the
previously interested citizens embark for this new frontier. With enough
supplies to get back home if stellar ignition fails, of course.

88 – First Solar immigrants arrive at Haberd's Brown Dwarf 629 and
prepare to convert it into a star system. The debris ring orbiting the
brown dwarf turns out to be thickest right at the distance from the
future star that they wanted to build their civilization, meaning any "worlds"
they might have planned on building would be right in the middle of an asteroid
freeway. While stellar ignition preparation continues, the homesteaders
decide to turn the disadvantage of this debris ring into an advantage.
They build their new homes right into one of the biggest asteroids
itself. They have to live in pressurized dugouts with almost no gravity,
but lacking gravity has its advantages too.

89 – First emotional plague behavior incident at the future site of
Human-Centauri. The perpetrator is given a choice of one year's private
confinement, or deportation back to Sol. She leaves. Many feel
the situation was not handled well and that new standards for dealing with
plague-characters should be adopted.

90 – Human-Centauri stellar ignition. A star is born.
Asteroid scaffolding construction crews can now work by the light of this new
candle, instead of their portable fusion furnaces.

93 – First Centaurian immigrants arrive on (Gregorian) June 5th to a
warm welcome at the still-under-construction Human-Centauri habitat ring.
The human inhabitants of Human-Centauri officially name June 5th "Grand Opening
Day". Sadly, a few Centaurian's are found to have character structures
tainted with their own species' version of the emotional plague, and have to be
sent back.

94 – Sirius: Light from the newly-ignited star arrives.
Sirians are flabberghasted that these independent malcontents could actually
pull it off. CN Leonis: First light from Human-Centauri
arrives. The Leonians are frankly amazed, but have had political and
economic problems of their own so can't pay it much attention at this point.

95 – Construction on the first Human-Centauri major asteroid has
progressed to the point where the Citizens start eyeing the second.
The asteroid is officially christened Human-Centauri I, but among the
inhabitants it's simply known as "The Capital.". 1.0 g centrifuges
start springing up in the more densely-human-populated areas, as places to keep
the human occupants from suffering muscle and bone mass degeneration.

97 – First light from Human-Centauri reaches Sol.

98 – First light from Human-Centauri reaches Alpha Centauri.

100 – First disgruntled Human-Centauri reject arrives back at Sol.
Her story blurts "Human-Centauri unfair!" in tabloid-like news media across the
system. Those who've actually met her tend to agree with the
Human-Centaurians' decision, however.

101 – Second major Human-Centauri asteroid now inhabited with its own
underground centrifuges; due to the influx of new waves of immigrants,
Human-Centauri II is now christened "New Mars". Another large asteroid
is commendiered as a "greeting area" where prospective Human-Centauri citizens,
emotional plague bearing or not, may arrive and live before being accepted or
rejected.

113 – Human-Centaurian projections indicate that their population may
exceed the capacity of all three major asteroids within the century.
Plans are laid for a "higher class" neighborhood, consisting of the future
Human-Centauri IV and V, the two largest asteroids in the star system.
(Human-Centauri I was chosen not for its size, but for the usefulness of the
ice and carbonaceous materials near its surface.)

124 – Human-Centauri IV added to the artificial star system's usable real
estate. Its inhabitants name it "New France." It is considerably
larger than any of the first three asteroids.

143 – Human-Centauri V inhabited. Human-Centauri VI is not planned
for the near future.

151 – SBI issues Arnold Hassleberg NK438CH5, a top-of-the-line Bussard
fusion scramjet, which has external inflatable fuel tanks that allow it to
reach a much higher ramscoop speed before burnout, and which is built to
sustain a continuous 2g of acceleration or deceleration.

162 – Start of the story. Mad Scientist test-detonates first Phased
Antimatter device on UV Ceti IV, destroying the planet (and himself). SBI
observers Arnold Hasselberg and Jerry Redlands discover double-sided hole in
space (filled with utter darkness) at the flashpoint. Arnold accidentally
falls into hyper hole and is believed gone forever. Jerry violates orders
and sends the secrets of the terrible, planet-rending destructive power of the
Phased Antimatter Bomb to all five star systems.

177 – Jerry's data-transmission signal reaches all five systems
simultaneously. The problem of What Happened At The Flashpoint becomes
the hot topic in the various scientific communities. Sirius's physicists
quickly stumble upon the answer to the riddle of the Phased Antimatter Bomb by
codifying the Energy Density Limit. The news is sent to the other four
star systems. Since the realization involves the fact that the Phased
Antimatter Bomb essentially produced a four-dimensional stairstep into a
parallel 3-D space, the bomb is re-christened the "Hyper Bomb".

186 – News of Sirius's discovery reaches Sol and Alpha-Centauri.
Sol had gotten pretty close to this answer themselves, but Sirius still beat
them to the punch. Alpha Centauri has a large enough positron stockpile
to attempt building a hyper hole tunnel between themselves and another star
system. Since trade with Sol would be the most profitable to them, and
since Sol also has the largest positron stockpile of all five systems, Alpha
Centauri sends a message to Sol detailing how the two of them could build a
hyperlink.

190 – Alpha Centauri's hyperlink idea reaches Sol. The Solar
Federal government had a similar idea a couple of years ago, and they're
ecstatic to try it. They send the go-ahead signal to Alpha
Centauri. They even send precise aiming and timing information to Alpha
Centauri as to when (5 years hence) and where (between the orbits of Jupiter
and Saturn) they're going to blow their hyper bomb. They figure that even
if Alpha Centauri doesn't agree, or misses their target, or the theory doesn't
work, they'll get to put the hyper bomb through a real domestic test.

194 – Sol's acceptance and plans reach Alpha Centauri. The A-III
government finishes its own hyper bomb and starts lining it up to within a
thousandth of an arc-second of the precise location Sol said they'd be
detonating theirs.

195 – Both Sol's and Alpha Centauri's hyper bombs go off. The aiming and
timing were superb on both ends. Despite the monumental odds against
them, the hyper link was successfully created. (One photographer poised
behind the Sol bomb was killed, though, since no one had anticipated the
foreflash from the other guy's hyper bomb would come though the hole to
their own side.) The English-language radio transmission of "Can
you hear us?" was greeted with an English "yes!" from the other end almost
immediately. Less than a week later, the first manned (Centaurianned?)
Alpha-Centaurian spacecraft crosses the hole to Sol space, and the next day,
Sol's first passenger craft voyages to Alpha Centauri in a like manner.
Sol and Alpha Centauri immediately relay plans for similar hyper holes to
Sirius and CN Leonis, respectively.

196 – Analysis of the blast and hyper holes indicates that there was more
of a margin for error on angular alignment than had been anticipated (which was
why the first dual detonation had been successful). Sol and Alpha
Centauri each place a communications relay station in matching orbit with its
end of the Sol/Alpha-Centauri hyper link.

197 – Border patrol functions are added to the communications relay
stations, first by Sol and then by Alpha-Centauri within the same year.

198 – To ensure the border patrol stations stay put, Sol and Alpha
Centauri each move an asteroid a few miles in diameter into hyper hole orbit,
and anchor their station to it.

201 – Sol's good news arrives at Sirius. They suspect a trick, but
have been looking for an excuse to test their own hyper bomb. Like Sol
before them, they transmit intended coordinates and timing back to the system
that suggested it to them.

203 – News of the Sol/Alpha Centauri hyper hole arrives at CN
Leonis. Although it would deplete them of almost every positron they've
cultivated (they'd been stockpiling primarily antiprotons prior to the success
of the Phased Antimater Bomb), CN Leonis agrees to detonate their own hyper
bomb and transmits the intended time and position to Alpha Centauri.

208 – The Sol/Sirius hyper hole detonations work. Communications
relays are set up on either side of the hole immediately. Sirius begins
its second hyper bomb and asks its other neighbor, Human-Centauri, if they'd
like to link with them.

212 – The Alpha Centauri/CN Leonis hyper hole detonations are a
success. Now Human-Centauri is the only one of the five major star
systems to be lightspeed-isolated. CN Leonis tells of this success to
Human-Centauri, and accelerates its positron collecting operations in an effort
to build another hyper bomb as soon as possible. (Not just for linking
with Human-Centauri, either; the Leonians, who are primarily Centaurian, are
wary of their species' homeworld. A planet-killer bomb would make quite a
deterrent.)

213 – Sirius's request to establish a hyper bomb link with Human-Centauri reaches Human-Centauri.
Positron collecting has been slow at best, but they figure they'll have enough in three or four years to
make an attempt. The details of where and when they intend to detonate are transmitted to Sirius;
since four years is only enough time for a one-way message between these two worlds, Sirius will not
have the option to ask them not to make the attempt if they so choose.

215 – A Leonian "Would you like to establish a hyper hole link with us?"
request arrives at Human-Centauri. They agree, but tell them it'll take
some time to accumulate the necessary positrons since they're already planning
to link with Sirius.

217 – Human-Centauri's "We're going to detonate" message arrives at
Sirius, who obliges them. The two systems successfully establish a
hyperlink and use the new trade route to request some extra positrons for their
proposed link with CN Leonis. Sirius refuses. Human-Centauri begins
the ten-year process of positron accumulation to produce the necessary 250 kg
of positronic antimatter for a hyper bomb.

218 – By using the four existing hyperlinks, the Leonians actually deliver 20
kg of their own positrons to Human-Centauri. They are really intent on
having a direct Human-Centauri link. The Human-Centauri Defense Force
gets a bit suspicious about this, but the go-ahead for the next link detonation
is given to the Leonian courier, who takes it back to CN Leonis.

219 – Human-Centauri completes its second hyper bomb. The communications relays on all the
existing hyper holes greatly facilitate the process of synchronizing their detonation with CN Leonis's.
Creation of the fifth hyper hole link is a success.

220 – The formerly small inhabited region on Human-Centauri's "greeting
area" asteroid expands into a tourist spot, as it is the only place in the
Human-Centauri system that noncitizens can go. An embassy is established
there.

223 – Sirius completes another hyper bomb. They do not use it to create a
hyper link with Alpha Centauri or CN Leonis, and have no intention of doing
so. For the first time in the history of post-first-contact space, a star
system holds the threat of planetary annihilation over its neighbors.

224 – Alpha-Centaurian intelligence discovers that CN Leonis has had their own spare hyper bomb for
at least as long as Sirius has. An emergency summit of representatives from all five governments is
held on Human-Centauri II. The first SALTY treaty is signed, banning positron stockpiling for any
purpose other than creating hyper hole links. All star systems begin a build-up of conventional
antiproton warheads and military spacecraft.

225 – Sirius and CN Leonis refuse to comply. Sol is discovered to
have made two hyper bombs since it coestablished the Sol/Sirius link.
SALTY II, requiring all hyper bombs to be phased out over six years, is
proposed and signed by four of the five systems (CN Leonis refuses), and, since
unanimous participation was needed, is rejected. SALTY III, a more
palatable solution allowing each star system to stockpile at most one hyper
bomb at a time, is signed unanimously. The border-patrol installations
on both sides of each hyper hole link are beefed up into massive "gate guards"
capable of holding their own against an entire carrier's complement of
fighters.

226 – Sol refuses to dismantle or use its second hyper bomb, giving excuses like "Well, what if a new
alien species showed up and decided to attack us?". SALTY III breaks down. Sol proposes SALTY
IV, which, after cutting through pages of legalese, basically says that everybody else gets to keep one
hyper bomb in reserve, but Sol gets to keep two. No other star system signs this treaty. Tensions
mount. To avoid threats of blockade, Sol reluctantly signs SALTY V, forcing them to dismantle their
second hyper bomb but (in a loophole their diplomats discovered) allowing them to stockpile as many
raw positrons as they liked.

227 – Discovering the SALTY V loophole, the other star systems demand another summit with Sol.
This one is held on Alpha Centauri A-III. After heated discussion and the threat of war, SALTY VI is
ratified, which does not limit the size of a positron or hyper bomb arsenal but requires that each star
system keep all of its positrons (and hyper bombs) in plain sight for the other systems to inventory.

228 – SALTY VI seems to be working. With the exception of Human-Centauri, which has only one
hyper bomb in reserve, all 5 star systems have two hyper bombs and some extra positrons on the
way to building a third bomb.

229 – Alpha Centauri discovers a third Solar hyper bomb that they've been
keeping hidden. Sol's transit privileges through Alpha-Centaurian space
are revoked. Yet another conference is held, this time on Human-Centauri
II. While James Carter (Sol's representative) is en route to the
conference through Sirian space, he receives an encrypted message from the SBI
telling him that that a secret extra Alpha-Centaurian hyper bomb has just been
discovered. At the conference, Sirius, CN Leonis, and even Human-Centauri
are strongly suspected of having an extra hyper bomb (or in the Leonians' case,
two) in reserve that they weren't telling the others about.
Blockade decisions fly around the room. Tempers flare, tolerance limits
break. Finally, Alpha Centauri's representative (Holsteader) declares war
on CN Leonis. And James Carter declares war on Alpha Centauri. And
Holsteader declares war on Sirius. And CN Leonis's representative
(Krammer) declares war on Human-Centauri. And Sirius's representative
(Håkan Brezhnev; at one point I thought of naming him Ivan Harlbjorg)
declares war on Sol. And on it goes, until every star system is formally
at war with every other star system.
Realizing the strategic threat of two hostile neigbors,
Sol decides to make a quick strike against their weaker neighbor so that they
can focus on their more powerful foe. They don't have the fighter
carriers to commit to a full-scale military win against Sirius, so they opt
instead to smash the bulk of the Sirian transmute-tanker fleet. This
hugely limits Sirian fuel supplies for over a year.

230 – A year into the war, Torra Zorra, Ken Tractor, and Jennifer Doe
receive The Message. They request a starship — something for which
little or no use has existed for over a decade — to make the
voyage to UV Ceti IV's remains. Yukariah Heap agrees. The Message
indicates that they had better get there inside of 10 years; unfortunately,
UV Ceti is over 13 years away from Human-Centauri. Only the Sol system is
close enough to UV Ceti to cut a non-hyper-hole interstellar voyage down to
less than 10 years of travel time. Taking a prototype interstellar
warship built for hypothetical colonizing missions (yet small enough to fit
through a hyper hole), they run a deadly gauntlet across Sirian space and past
three hostile gate guards into Sol space, and take off for UV Ceti.
Thankfully, Sol does not pursue, since the three are not maneuvering toward any
potential targets and the Solar military has its hands full with Sirius at that
moment anyway.
A quick relativistic calculation shows that a continuous
1g acceleration will not be enough to cross the 8.554 light-years from
Sol to UV Ceti in 10 years' time, but a continuous 2g acceleration
will. At 2g, it will take 4.734 years of rest-time [1.442 years "proper
time"] to reach the half-way point, at which point they will be travelling at
0.99479 of c (at which speed γ = 9.812). If you can sustain
2g, though, you don't have to accelerate all the way to the half way
point. You'll reach 0.95c in 1.446 years rest time, at which point
you can coast for 6.798 years, then decelerate at 2g for another 1.446
years — total travel time: 9.69 years. If you accelerate to only
0.92c (γ = 2.72), it'll take you 1.116 years of rest time to get
going that fast, duing which you'll cover 0.738 light-years; you'll coast for
7.08 ly at 0.92c, which'll take 7.69 years of rest time, for a total
trip time of 9.925 years.

236 – Sirius drops antimatter bombs on several major Human-Centaurian
metropolitan areas, including New France and New Mars.

237 – The war is going badly for Human-Centauri. Although CN Leonis
has been leaving them alone, Sirius has been dealing them heavy blows.
They need help. They give CN Leonis permission to transit their space to
put pressure on Sirius, since CN Leonis is at war with Sirius too. The
Leonians say they'll need to operate from the Human-Centauri habitat ring if
Human-Centauri is going to get their help. In one of its most
self-destructive long-term moves ever, Human-Centauri grudgingly allows the
Leonian military — including its Fanatic Brigade — to inhabit
Human-Centauri citizen territory. The emotional plague poisoning begins.

238 – Throwing off the gloves, CN Leonis authorizes its Fanatic Brigade
to use a Leonian hyper bomb on Alpha Centauri A III. They succeed, and
Alpha Centauri A III is half-shattered. The homeworld of all Centaurians
is reduced to a floating hulk. So much for the history, art, archaeology,
biology, paleontology, geology, etc., etc., of the planet. Thoroughly
appalled, Human-Centauri revokes its permission for CN Leonis personnel to
inhabit citizen areas and begins to round them up and herd them out, but the
social damage has already been done.

240 – The Chosen Three arrive at UV Ceti. No news has been beamed
to them, since the signals would've had to have originated from Sol. The
Messages are found to be from the "ghost" of Arnold Hasselberg, who points out
the Zero Drive that the Mad Scientist had developed before he shattered the
fourth planet. Ken recovers it, Jennifer tries to kill him, Torra Zorra
(in attempting to subdue her) accidentally kills her. They install and
test the Zero Drive, then use it to enter a Limbo (neither wholly in Real nor
in Parallel space) while moving through the hyper hole. (This is done by
calculating the movement of the hype hole through absolute space as it orbits
UV Ceti, and letting it envelop them while their zero-drive makes them stand
rock-still.) On the trip back, they learn the news of the Sirian bombings
of Human-Centauri's habitat ring, Human-Centauri's allowance of the CN Leonis
military into its citizen areas, and A-III's annihilation. They emerge
from the Human-Centauri end of the Human-Centauri/Sirius hole and, using the
decisive maneuverability the Zero Drive gives them, vanquish a Sirian assault
force just moments before they would've hyper-bombed Human-Centauri I.
They tell Human-Centauri about the impending End of the Galaxy, who tells of
this catastrophe to the other four star systems, who stop mucking about with
fighting each other because, darn it, the galaxy could end at any moment.
Ken Tractor and Torra Zorra then take the Sirian hyper bomb originally intended
to blow up their homeworld, go back into Limbo through the CN Leonis hyper
hole, race to the center of the galaxy, and (using the hyper bomb) squelch the
impending explosion of Sagittarius X in the nick of time. And everybody
lives happily ever after. (Until I write the sequel, that is.)

Centaurians feel perfectly comfortable wheeling around in public with no
clothes on. (It should be noted that some tribes of humans are at home
with their own public nudity, too, so this shouldn't come as too much of a
surprise.) The placement of the Centaurian genitalia means they aren't
normally visible while standing up, so even those few Centaurians with a
"Victorian" sense of shame can hide their anatomy without cloth.
Protective clothing is usually designed to protect from the wind rather than
the cold; the species' lack of endothermy means that wearing clothes to
"hold in ones own body heat" is ridiculous. When clothing is worn, its
colors are either terribly drab or the most striking, gaudy clashes of solid
toddler-toys-bright pastels imaginable to the human mind — and in either
case slight blemishes or stains will go completely unnoticed. (This is
all because of Centaurians' reduced color sensitivity.) Shoes are
sometimes put on infants' tender feet, and are often worn by adults whose feet
are more sensitive; but they always have a hole in the bottom for the
wheel. Body wraps that fit snugly below the mouths are another staple of
those Centaurians who wear clothes. Rarely will a Centaurian submit to
clothing that hangs down from the shoulders over any of the mouths, and all
clothing for the top of the body must have a hole big enough for the
eyes-and-ear stalk to fit through. Since the rank structure of human-inspired
militaries (such as the HCDF) requires the display of rank insignia,
Centaurians in the HCDF will wear a rank insignia on one or two arm bands
while on duty.

Since Centaurians can rest standing up, they don't use chairs. This makes
titles such as "chairperson" sound a little odd.

A deployer's fighter complement is called, as you might expect, its
squadron. Fighters are semi-intelligent in their own right, capable of
extremely complex tactics, strategic decision making, coordinating its actions
with other fighters in the same squadron, and following orders the way a
military pilot would.

The primary function of the fighter deployer is as a repair and resupply
station for its fighters. A fighter may burn a substantial fuel load and
discharge an enormous amount of destructive force in a single engagement; it
cannot afford to carry large stockpiles of protium and deuterium, or
ammunition, due to the added weight. Since fighters use
protium-deuterium hot fusion engines that can be throttled up in excess of
100g, but deployers cannot exceed the physiological g limits of
their crews, a deployer is considerably less maneuverable than a fighter.
It makes up for this deficiency by deploying its fighters a good distance away
from the action, and by being armed and armored to the teeth.

Personal weaponry includes all the good old-fashioned (but messy) weaponry
available at the end of the 20th century, plus: stundart pistols tailored for
human or Centaurian physiology, a kevlar-like high-temperature plastic for body
armor, ...

Whipple armor: A multi-layered steel-vacuum sandwich, similar to a
modern Whipple shield but with more (and progressively thicker) layers.
It's designed to turn an impacting hypervelocity projectile into a
progressively thinner and thinner cloud of plasma, until it's too weak to
penetrate the inner layer(s). The outermost layer is often made
reflective to repel attacks by lasers.

Missiles: Missiles are small, unintelligent spacecraft designed to ram
their target. The bulk of their mass consists of protium and deuterium
fuel for their tiny 100g hot-fusion engine. They're usually shaped
like long, narrow cylinders so that they can fit in missile launch tubes.
The missile launch tubes themselves are very weak mass drivers, which throw
their cargoes away from the launching spacecraft at only a few kilometers per
second. This isn't done to give a missile a hefty initial velocity
— a few km/s is peanuts compared with the missile's total dalta-v budget
— it's done to put some distance between the missile and the launcher
before the missile lights off its (rather destructive) engine. Missiles
can also be deployed without a launch tube, e.g. connected to hard points on
the outermost layer of the spacecraft's whipple armor as external ordnance, but
care must be taken before starting such a missile's engine to ensure that it
neither blasts the launching spacecraft with its exhaust nor rams into it.

Too small for an S.I., missiles rely on radar emitters and passive thermal
sensors to home in on a single designated target, and they can be fooled
by thermal decoys (flares/"chaff") dropped at the last moment. The
hot-fusion engine has a highly gimballed nozzle for thrust vectoring; in many
shorter missiles, this is the only means of steering, while in most others, a
thruster quad on the nose allows the missile to rotate more rapidly.
Extremely rapid rotation is absolutely essential; a missile needs to point its
thrust vector exactly where it's needed at an instant's notice, because its
target will probably be undergoing unpredictable evasive maneuvers,
particularly right before impact. A missile designed to hit a hardenened
target (a target with whipple armor like a fighter's) generally stays in one
piece to minimize the area its impact will be spread over; a missile designed
to shoot down an unarmored target in deep space often contains a small
fragmentation warhead that blows the missile into many tiny pieces just before
impact, to maximize the chance that at least one piece will score a hit.
Cruise missiles are larger, so that they can carry more fuel, and will accept
encrypted orders from the launching spacecraft in mid-flight to change targets
or abort (assuming the order arrives in time with the light-speed delay).

Drones: Both fighters and their deployers may also carry extremely small
remotely-controlled unintelligent spacecraft called drones. A drone
resembles an EVA pod in 2001: A Space Odyssey or the escape pod seen at the
beginning of Star Wars; it's a small unmanned spacecraft similar to a missile
that carries a single secondary-caliber spacecraft-to-spacecraft direct fire
weapon — a high-energy laser, a proton beam, even an electromagnetically
launched missile or two of its own. Like a missile, a drone has a small
proton-deuterium hot-fusion engine. Not only is a drone too cheap for its
own SI Controller, it's too small for a useful radar emitter; a nearby fighter
or manned spacecraft must provide it with weapon locks, and must pass along any
maneuvering instructions more complicated than "home in on target."
Kinetic-kill drones aren't even reusable; they're basically a one-use
electromagnetic gun with an engine. The gun destroys itself on firing,
and the recoil does so much damage to the engine that it's cheaper just to
scrap it and buy a new one than it is to repair; in fact, the remains of the
spent drone will be sent flying backwards nearly as fast as the slug is sent
flying forwards!

Ascenders and Atmospheric Descent Pods: If an offensive campaign gets to
the ground assault phase, victory is all but assured. Any orbital
defenses will have been taken out first (including the gate-guard sized space
stations protecting any important planet), then any ground-based orbital strike
installations and air/spaceports capable of launching orbital strike vehicles;
then, any military targets exposed to the sky can be picked off at leisure from
orbit. Only after the enemy's military installations have been whittled
down to next-to-nothing and their means of communications severed or interfered
with as much as possible (a deaf enemy is a confused enemy, and a confused
enemy is a vulnerable, low-morale enemy), will troops be landed on the
surface. The least expensive means of landing troops is an atmospheric
descent pod (essentially a large Mercury spacecraft) — this requires a
substantial atmosphere and cannot re-ascend once it has landed. For
hit-and-run raids, or for temporary troops, an ascender can be used.
These fusion powered aerospace craft are hardly taller than an Apollo
spacecraft and have enough fuel to land, ascend to orbit at 9 g's, and even
attain an interplanetary trajectory if necessary. An ascender's nosecone
is plated in nonablative Heat Bolide™ (similar to Space Shuttle tile
material but not nearly as expensive), allowing it to be used for re-entry
aerobraking as well as hypersonic ascent.

Of course, lasers aren't 100% efficient, so the laser's power-draw requirements
will be several times higher than its beam-power output. (And the power
that doesn't go into the beam, due to the laser's inefficiency? That's
gonna be heat. You'll need radiators, or a way to dump that heat
into the exhaust stream.)

Since the power released from the fusion of 150 grams of protium into helium
per second is 94.5 terawatts, we might be able to afford the energy
drain caused by this sweeping UV laser. It all depends on how efficient
our laser is.

The good news is, all this may be unnecessary. About half of the hydrogen
in the Local Fluff — and nearly all the hydrogen in the broader and
thinner Local Bubble — is already ionized. Phototonization
would only be necessary directly ahead of the physical structure of the
starship, to ensure that it doesn't smack into any material that doesn't get
scooped up.

Electrostatic scoops: the proton vs. protium replenishment problem

The interstellar medium in the Local Fluff consists of about 50% ionized
hydrogen (protons) and 50% non-ionized hydrogen (protium). Protons are
positively charged, and so can be drawn in magnetically or electrostatically;
protium is not, and cannot so be drawn in. A starship will have a
forward-facing UV laser that constantly sweeps the area immediately in front
of the spacecraft, to turn all protium directly in front of the 'craft into
protons, thus allowing them to be scooped in instead of slamming against the
forward hull.

This means the stuff a starship scoops up will be positively-charged hydrogen
ions, instead of neutral hydrogen. Theoretically, a magnetic scoop could
suck up the free electrons just as easily as it could suck up the hydrogen
ions, and could in fact inhale both at the same time; but with an electrostatic
scoop, you can only suck up one or the other. There are two problems with
this, a minor one and a major one:

(1) In a scramjet, the scooped material is run through QC&C nuclear
fusion. The result of the nuclear fusion of two protons is a deuteron and
a positron. If none of the incoming material is electrons, you won't have
any electrons to annihilate your positron with. This means you must dump
your positrons directly out of the exhaust. This could theoretically
make the trip much more perilous for the next starship that follows your path
through space, except that by that time the positrons will have had time to
mix with the electrons that are naturally present in all that ionized hydrogen
out there. You might get a few gamma ray flashes in your wake, but this
is a minor problem.

(2) A more serious problem comes when it's time to undergo braking. You'd
like to be able to use the braking phase to replenish the hydrogen (protium) in
your starship's fuel tanks, which you had to expend to get it up to speed in
the first place. But you're not scooping up protium, you're scooping up
protons. If you tried to store those, you would very quickly pick
up an electric charge imbalance, which is a very bad thing. You would
need to alternate the electric charge on the scoop from time to time, to
attract electrons instead of protons; or you would need to be able to scoop up
neutral hydrogen instead of ionized hydrogen, which only Poul Anderson can get
away with; or you would need to forego the whole process of replenishing your
fuel tanks while braking and instead carry enough fuel for both the
outbound acceleration phase and the final braking phase, which
doubles your rocket-based delta-v requirements. Another possible solution
to this dilemma is to ground your fuel tank, so that the charge imbalance ends
up spread out over the outer hull. Then as the starship accumulated a
net positive charge, electrons from nearby space (the ones that were bound to
the ionized hydrogen before it became ionized) would naturally be attracted to
the hull, and would neutralize the ions in its fuel tank on their own.
This might work with a starship with a magnetic scoop, but a starship with an
electrostatic scoop (like Mercurand) would have trouble overcoming the net
negative charge of its drogue-wire.

An analysis of the feasibility of Alan Bond's RAIR

The Ram-Augmented Interstellar Rocket, or RAIR, was once considered as a
promising compromise between the true Bussard ramscoop and a pure rocket.
In theory, you could scoop up the interstellar medium and use it as extra
reaction mass for your fuel combustion to push against.

However, there are two problems.

First, the interstellar medium is exceptionally thin. In the "local
fluff" in which the sun and a few neighboring stars are embedded, the density
of the interstellar medium is only about 1 atom of hydrogen for every 10 cubic
centimeters. (Outside the local fluff it's about half that.) This
means that if your starship had a ridiculously huge 1000 km radius scooping
field, at 10% of the speed of light you'd only be scooping up 15 grams of
hydrogen per second. Even a modest spacecraft would have to weigh in at
at least 100 tonnes empty to carry anything even remotely interesting, and
that's the empty mass, before the mass of its unexpended fuel is added
in. Accelerating a 100 tonne fusion rocket at 1 g requires burning
28 grams of protons. The extra 15 grams you're scooping in at 0.1
c aren't going to provide much to push against.

Secondly, the reaction mass isn't standing still when you scoop it in.
If you're moving at 0.1 c, those 15 grams of interstellar medium are
zipping down your gullet at 30,000 kilometers per second.

This second point is actually the most significant. Remember, dumping the
energy you get from burning your fuel into the exhaust increases its kinetic
energy — but it's the change in the exhaust's momentum that
drives your starship forward. Adding a given amount of energy to 15
grams of matter that are already going at 0.1 c is going to give you a
much smaller momentum change than adding that same amount of energy to 15
grams of matter that are standing still (relative to you).

How much smaller? Well, when increasing any object's velocity, the
increase in kinetic energy is:

ΔKE = ½m (v0 +
Δv)2 –
½mv02

... where m is the mass of the object, v0 is its
initial velocity, and Δv is the increase in its velocity.
The spent fuel has a v0 of zero; the incoming ram-scooped
material has a v0 equal to the speed of your spacecraft.

So, for comparison, to give 15 grams of spent fuel a nudge of 1000 km/sec
would take:

However, it's possible to use some of the kinetic energy of the oncoming
interstellar medium to your advantage. You can "mix" it with your fusion
reactor's own exhaust stream, so that some of its momentum is transferred to
your fusion fuel products.

Then, you're not talking about "dumping" the energy from your fusion burn into
the ram-scooped matter stream anymore. You're talking about "pooling" the
kinetic energy of the oncoming material with the energy released from fusion,
and applying that combined energy total to the entire combined mass of
your exhaust.

Say you're going 0.2 c. At that rate, you're taking in 30 grams of
interstellar medium per second. Normally, if your 100 tonne spacecraft
were a pure rocket, burning 28 grams of onboard protons over the course of one
second would produce an impulse of 980,000 kg m/s, giving you an acceleration
of 1.0g. But if we combine this with the 30 grams of inert mass
we've just scopped up, we get:

This advantage dwindles, however, the more we increase the spacecraft's
mass. If we assume that 100 tonnes is the empty weight of our
starship, and at 0.2 c we're still carrying enough fuel for another
~0.1 c worth of acceleration (again assuming near-perfect nuclear fusion
with a 0.1c exhaust velocity), that means our spacecraft currently has
a mass of e times its empty weight, or 272 tonnes. It takes about
75 grams of proton fusion to accelerate this much mass at 1.0 g
in a pure rocket design. If you add 30 grams of RAIR material to this,
your new optimally-mixed acceleration works out to only 1.07 g.

But now suppose that instead of using a "normal" magnetic scoop, we use a
much more efficient scoop, such as the Matloff and Fennelly electrostatic
scoop-line or the similar design that I'm calling "the Drogue" on
Mercurand. Let's say that at 0.2 c, this scoop can gather up a
whopping 100 kg of interstellar medium per second. Then, for a 100 tonne
spacecraft, we get:

... which would impart an acceleration of 1.157 g to the
spacecraft. Bleah. That's hardly what I'd call an improvement.

Mercurand's antimatter engine:

As originally designed, Mercurand carried 100 tonnes of antiprotium, and the
rest of the spacecraft massed an additional 100 tonnes, including 1 tonne of
normal protium it carried for its boost phase.

When burning its internal hydrogen supply, 1 antiprotium atom is annihilated
with 1 protium atom, and the resulting thermal energy is used to accelerate an
additional quantity of protium as exhaust. Each kg of protium and
antiprotium annihilated yields 1.8 x 1017 J of kinetic
energy. Let's see how much momentum this will impart to Mercurand when
applied to different masses of propellant. Since Mercurand only carries 1
tonne of koinohydrogen, we can assume its mass will stay constant at nearly
200,000 kg for the duration of this non-scooping boost phase. This
1.8 x 1017 J of kinetic energy will have to be split
between the exhaust and Mercurand in such a way that the net change in the
momentum of both bodies is 0:

Velocities for ΔKE = 1.8 x 1017
J, 200 tonne spacecraft

Propellant mass

Exhaust velocity

Spacecraft Δv

1 kg

γ = 3 (0.9428c)

4240 m/s

10 kg

189,732,000 m/s

9486.6 m/s

100 kg

59,985,000 m/s

29,992 m/s

1,000 kg

18,920,000 m/s

94,632 m/s

1,000,000 kg

245,000 m/s

1,225,000 m/s

1,000,000,000 kg

268 m/s

1,341,510 m/s

1,000,000,000,000 kg

0.268 m/s

1,341,640 m/s

Note: Other than the first entry, none of these
velocities are adjusted for special relativity

So if we can only afford to expend 1 kg of our internal protium supply as
propellant per kg each of protium and antiprotium annihilated, we only get
4240 m/s of delta-v. That's not very much, is it?
Expend all 1000 kg of protium, and you've only got 2120 km/s of delta-v,
barely enough to accelerate you to 7 permil. You'll need at least 10
permil, preferably 100 permil, to sweep up the interstellar medium at a decent
rate, and that doesn't even count the 4000 km/s they'll need to expend to
accelerate and decelerate across the 200 million km gap between the Sirius/HC
and Sirius/Sol hyper holes.

If we allow Mercurand to carry 100 tonnes of protium instead of just 1 tonne,
that changes the picture dramatically. Now we can afford to dump 100 kg
of propellant into the exhaust for every 1 kg of protium and 1 kg of
antiprotium annihilated. With a fully loaded mass of 300 tonnes, an
"empty weight" after expending all propellant (but not all antiprotium) of
199 tonnes, an an exhaust velocity of 60,000 km/s, that gives us a total
delta-v budget of 24,630 km/s, or 82 permil. Even if we assume that the
above table is bogus, and that all the kinetic energy from the
annihilation can be funneled completely into the exhaust, that still gives us
an exhaust velocity of 60,000 km/s, because the spacecraft is so much more
massive than the exhaust fraction that the difference is too tiny to matter.

This is reasonable. Mercurand, therefore, has an empty mass of 100
tonnes, and carries 100 tonnes of whiteflake antiprotium in one tank and 100
tonnes of cryogenic protium in another tank, giving it a total "takeoff weight"
of 300 tonnes.

But let's see what the optimum would be. We agree to limit the
amount of antiprotium we annihilate to 1 tonne during all non-scoop
operations. Annihilating this with exactly 1 tonne of protium yields
1.79751 x 1020 J of total kinetic energy. Because
the amount of kinetic energy is so high, and the amount of "dead weight"
propellant it's applied to is so small, we can't just use &frac12mv2
to calculate the exhaust velocity; it will be necessary to adjust for
relativity. The relativistic kinetic energy of rest-mass m is of course
(γ−1)mc2, which means that γ =
(1.79751 x 1020 J / mc2)
+ 1 = (2000 kg / m) + 1 = 1 / sqrt(1 −
v2/c2).

If we have the relativistic exhaust velocity, we can use the regular
Tsiolkovsky rocket equation. Although 2 tonnes of the material that is
expended is annihilated and is not propellant, the mass-energy from that
annihilation is used to accelerate the propellant to relativistic speeds.
Thus the propellant's increased relativistic momentum would make it behave as
though it were actually 2 tonnes heavier. So, if we vary how much
"dead weight" propellant we allow Mercurand to carry, in the form of protium
that doesn't get annihilated, what does Mercurand's total non-scoop
delta-v budget work out to?

Delta-v budgets for 199 tonne "empty" spacecraft

Starting mass

Propellant mass

Unadjusted exhaust velocity

Relativistic exhaust velocity

Total Δv

202 tonnes

1 tonne

599,585 km/s

282,647 km/s

4,229 km/s

211 tonnes

10 tonnes

189,605 km/s

165,717 km/s

9,703 km/s

301 tonnes

100 tonnes

59,958 km/s

59,076 km/s

24,446 km/s

401 tonnes

200 tonnes

42,397 km/s

42,082 km/s

29,485 km/s

501 tonnes

300 tonnes

34,617 km/s

34,445 km/s

31,803 km/s

601 tonnes

400 tonnes

29,979 km/s

29,867 km/s

33,012 km/s

701 tonnes

500 tonnes

26,814 km/s

26,734 km/s

33,664 km/s

801 tonnes

600 tonnes

24,478 km/s

24,417 km/s

34,002 km/s

901 tonnes

700 tonnes

22,662 km/s

22,614 km/s

34,152 km/s

951 tonnes

750 tonnes

21,894 km/s

21,850 km/s

34,178 km/s

961 tonnes

760 tonnes

21,749 km/s

21,706 km/s

34,180 km/s

971 tonnes

770 tonnes

21,608 km/s

21,566 km/s

34,183 km/s

981 tonnes

780 tonnes

21,469 km/s

21,427 km/s

34,182 km/s

1,001 tonnes

800 tonnes

21,199 km/s

21,159 km/s

34,181 km/s

1,051 tonnes

850 tonnes

20,566 km/s

20,529 km/s

34,164 km/s

1,101 tonnes

900 tonnes

19,986 km/s

19,953 km/s

34,133 km/s

1,201 tonnes

1,000 tonnes

18,961 km/s

18,932 km/s

34,032 km/s

2,201 tonnes

2,000 tonnes

13,407 km/s

13,397 km/s

32,198 km/s

Note that there appears to be a "sweet spot" between the 971 and 981 tonne
entries. Adding more propellant past about that point actually
reduces your total delta-v budget. At the time of the Pentagon
War, this optimal mass ratio — around 4.9 for a craft carrying about half
a percent of its empty weight in antimatter — is known as the
Heisenblatt-Sturnbridge ratio. (Confusingly, the ~780-to-1 ratio
of protium to antiprotium, which the engine will consume while producing its
thrust at this optimal delta-v level, is also called the
Heisenblatt-Sturnbridge ratio.)

Now . . . what about after Mercurand has expended all of its
onboard propellant, and has to rely on Drogue-gathered interstellar ionized
hydrogen both for annihilation material and reaction mass?

In chapter 9, they accelerate to 6-and-two-thirds permil in the Sirius system,
then decelerate back down to 1 permil, then do a powered turn to hit the hyper
hole bound for Sol space. The powered turn consumes 1.57 permil of
delta-v, so their total delta-v expended up through the end of the turn comes
to 13.9 permil. This leaves them with 68.1 permil of delta-v that they
can use to accelerate to interstellar speeds before running out of
propellant. This ignores the potential additional propellant they could
pick up by deploying the Drogue during this "runway" phase, but let's assume a
worst-case scenario and assume that they manage to accelerate to 69 permil at
the point their koinohydrogen runs out.

So, at 69 permil, how much interstellar ionized hydrogen will they be sweeping
up per second, within the local fluff?

We can assume that the Drogue performs as optimally as Matloff and Fennelly
suggest it might, with an effective gathering radius of 100 000
kilometers. At 0.069c, such a scoop would sweep out a volume of
6.5 x 1023 cubic meters, or
6.5 x 1026 liters. At 50 hydrogen ions (protons) per
liter, and 1.67 x 10-27 kg per proton, that works out to
54 kg of hydrogen ions per second that could theoretically be scooped up at
this speed.

Let's assume we're not willing to annihilate more than 1/1000 of the incoming
material, so that the rest is just deadweight reaction mass. 0.1% of
54 kg is 54 grams. Annihilating 54 grams of matter with 54 grams of
antimatter produces 9.7 x 1015 Joules of energy.
If we funnel all of that energy into the kinetic energy of the exhaust,
operating from the (incorrect) assumption that we're accelerating it from a
dead stop relative to the spacecraft (which we're not), the exhaust velocity
will be about 18,900 km/s. Throwing 54 kg aft at 18,900,000 m/s will
increase Mercurand's forward velocity by 5100 km/s, or roughly half a
million g. Clearly, this is far more thrust than we need.

Now . . . what's their total delta-vee budget for chapters 14 and
onward? I.e. for maneuvering in Limbo, and fighting the invading Sirians in
HC space?

For the return trip, their hydrogen tank is full (100 tonnes), but their
antihydrogen tank is half empty (only 50 tonnes). Worse, their drogue gets
hopelessly tangled and has to be ejected. They will not be able to gather
any interstellar hydrogen or stellar wind. They have to run entirely
on what they have stored.

Let's assume they're willing to use all of their stored antihydrogen
this time. They are in pretty desperate straits, after all. This brings
us back to the first case we considered above: 1 kg propellant per kg each of
protium and antiprotium annihilated. Their exhaust velocity will be γ =
3 (0.9429c). We need to convert that to its nonrelativistic equivalent
for purposes of the Tsiolkovsky rocket equation. Since we're imparting 2 kg *
c2 Joules of energy to each kg of propellant, assuming all of this
energy gets turned into kinetic energy of the exhaust, we get an "effective
exhaust velocity" (for purposes of the Tsiolkovsky equation) of exactly
2c (600,000 km/s). Initial mass of Mercurand is 250 tonnes, final
(empty) mass of Mercurand on fuel exhaustion is 100 tonnes. Applying the
Tsiolkovsky equation, we get:

Total Δv = 600,000 km/s * ln (250/100) = 549,774 km/s

... or about 1830 permil. Let's see how this synchs up with the relativistic
Δv equation from Nyrath's "Slower than Light" webpage, which says that
Δv = c * Tanh[(ve/c) * ln(R)]. Plugging the numbers in, we
get:

Total Δv = 300,000 km/s * Tanh[0.9429 * ln (250/100)] = 209,489 km/s

... which is considerably lower than what we get from my equation. Note that
the Δv that results from this equation is corrected for Relativity, and
assumes a spacecraft starting with velocity 0 and spending all its propellant
accelerating away (or toward) a fixed observer. If half of this Δv is
used to speed up and the other half is used to slow down, the peak velocity
in the middle will be higher than 0.5*Δv.

Still, even if it weren't, that's nearly 700 permil of delta-vee, more than
enough for any maneuvering Mercurand might have to perform.

101,300 s: Mercurand and fighter are within short weapons range of each
other

Note that, due to the bulk of the Sirius/Sol Second Guard, Mercurand does not
want to come directly into the hyper hole. Assuming the Second Guard is
100 km in diameter (50 km in radius), and that it's 3000 km from the hole,
Mercurand would have to come in at an angle of at least 1 degree to avoid
colliding with the Second Guard. Then again, no Second Guard is going to be
anywhere near that big, if it has to do station-keeping relative to one face of
a hyper hole that's rotating. The fuel costs would be prohibitive.
Instead, it would make more sense for the Second Guard to be only 10 or 20 km
in diameter, which greatly reduces the need for Mercurand to come in at an
angle.

Note also that, despite Ken's insistence that they can't afford to waste any
deceleration while they're crossing the fighter's engagement envelope, there's
an option Ken didn't consider. Let's say they REALLY miss the mark, and reach
the turn-start point going a whopping 420 km/s instead of the 300 km/s they
need. Mercurand could still brake to a dead stop in only 4,410,000 km, which
would leave them on a line nearly perpendicular to the Sirius/Sol hyper hole's
face 4,500,900 km away. They could then accelerate directly toward the hyper
hole and be going up to 424 km/s (over 1.4 permil) by the time they reach it.